Hi, I recently ordered some spyder headlights with the preinstalled hid kits for my 2004 jeep grand cherokee and I was wondering if I needed to order some of the warning/anti flickering cancellers too? I've looked but I haven't been able to find an answer for sure. Does anyone know?

The only time you'd need those is if you're running all LED bulbs in your turn signals and parking lamps. If everything is LED, then you'll get that fast flash garbage. If you're just fitting a new set of headlights with HID's, and re-using your existing incandescents in the parking lamp area, you'll be fine.